This invention relates to tube-launched, optically-sighted, wire-guided (TOW) missiles and in particular, to a method and apparatus for launching a number of missiles at separate targets and then simultaneously guiding the missiles to each target.
TOW missiles have been in development for some time and have been adapted for a variety of uses. The missiles can be ground launched by a soldier in a land based vehicle or launched from an airborne vehicle such as a helicopter. Regardless of whether ground or air launched, a gunner looking through a sight first identifies a target such as a tank in his field of view and then launches a single missile at this single target. During target sighting and missile tracking, the gunner keeps the target lined up in the cross-hairs of his sight. The position of the missile relative to the target is continuously monitored and correction signals are sent to it, through guide wires, to direct it to the target.
Tracking and guidance systems for TOW missiles have been developed so the missile can be guided to the target through a battlefield obscured by smoke or fog, or at night. Further, these systems have the capability to identify countermeasures taken by the enemy to prevent the missile from hitting the target. Once the countermeasures have been identified, the systems can avoid them and thus not be misled into steering a missile away from its target.
Heretofore, TOW missile systems have not had the capability to engage more than one target at a time. In the close combat situation which occurs on a battlefield, the gunner must continuously expose himself to risk as he sequentially engages a series of targets.
Studies have shown that a multiple target engagement (MTE) capability in TOW missile systems would yield significant advantages. In one study, for example, it has been demonstrated that the loss-exchange ratio (LER) improves dramatically in favor of one who has a MTE capability. (The LER is a measure of how much damage is inflicted by one side in an exchange in proportion to how much damage is inflicted by the other side during the exchange.)
Implementation of an MTE capability gives rise to a number of problems. A first of these is multiple missile tracking capability. In present TOW systems, for example, there is launch phase tracking and post-launch phase tracking. During the missile's launch phase, a beacon operating in one region of the light spectrum is used for tracking. When the missile's fuel is exhausted and its flight engine shuts down, a second beacon is activated which emits light in a different region, and the missile is now tracked by either the first or second beacon depending upon how obscure the battlefield is and the countermeasures taken by the other side. In an MTE system, more than one missile may be launched, with the missiles being launched in rapid succession. This now requires a tracking system to simultaneously track missiles from radiation in various regions of the spectrum and not lose track of any of the missiles.
A second problem involves target location by the gunner. As discussed above, the gunner, in previous TOW systems, positioned a cross-hairs in his sight on a target to be hit. He then kept the cross-hairs trained on the target to help guide the missile to the target. With multiple targets, it is not possible to do this. Consequently, the gunner needs a way to easily identify and "tag" individual targets which may be anywhere in his field of view. The system now has to keep track of each separately moving target, as well as keep track of which missile is directed at which target.
A third problem involves control of the sight to keep the targets within the gunner's field of view. A battlefield situation is dynamic. A target is not necessarily going to remain in one place during the time it takes for it to be identified as a target and for a missile to be launched at and to hit it. In a single target situation, this poses no problem because, again as discussed, the gunner keeps the cross-hairs in his sight trained on the target. In multiple target systems, the situation is quite different. With two or more independent targets moving about the battlefield, the line-of-sight must be controlled so to keep all the targets being tracked within the field of view.